Micro-fluid ejection heads are useful for ejecting a variety of fluids including inks, cooling fluids, pharmaceuticals, lubricants and the like. A widely used micro-fluid ejection head is in an ink jet printer. Ink jet printers continue to be improved as the technology for making the micro-fluid ejection heads continues to advance. New techniques are constantly being developed to provide low cost, highly reliable printers which approach the speed and quality of laser printers. An added benefit of ink jet printers is that color images can be produced at a fraction of the cost of laser printers with as good or better quality than laser printers. All of the foregoing benefits exhibited by ink jet printers have also increased the competitiveness of suppliers to provide comparable printers in a more cost efficient manner than their competitors.
One area of improvement in the printers is in the print engine or micro-fluid ejection head itself. This seemingly simple device is a relatively complicated structure containing electrical circuits, ink passageways and a variety of tiny parts assembled with precision to provide a powerful, yet versatile micro-fluid ejection head. The components of the ejection head must cooperate with each other and with a variety of ink formulations to provide the desired print properties. Accordingly, it is important to match the ejection head components to the ink and the duty cycle demanded by the printer. Slight variations in production quality can have a tremendous influence on the product yield and resulting printer performance.
In order to improve the quality of the micro-fluid ejection heads, new techniques for assembling components of the heads are being developed. For example, instead of separately forming nozzle holes in a metal or polyimide nozzle plate material that is then adhesively attached to a thick film layer on a semiconductor substrate, a dry film photoimageable material may be laminated to an imaged and developed thick film layer made of similar materials on the semiconductor substrate. Lamination of the dry film photoimageable material to the thick film layer may be conducted by placing a photoimageable thick film layer on the substrate and passing the substrate containing the thick film layer between two heated rollers which exert a chosen pressure on the substrate and thick film layer. Fluid supply slots are formed through the semiconductor substrate up to the thick film layer. The thick film layer may then be exposed through a photomask and developed to form flow features therein. The dry film photoimageable material may then be laminated to the imaged and developed thick film layer. Another photomask is used to image the dry film photoimageable material which is then developed to provide nozzle holes.
A problem with this method of making a micro-fluid ejection head structure 10 is that during the lamination process of the dry film photoimageable material 12 to a thick film layer 14 on a semiconductor substrate 16, the dry film photoimageable material 12 can sag down into the fluid supply slot areas 18 in the semiconductor substrate 16 as illustrated in FIG. 1. If lamination of the dry film photoimageable material 12 to the thick film layer 14 is performed before fluid supply slots are formed in the substrate 16, the dry film photoimageable material 12 can sag down and adhere to the substrate 16 in the fluid supply slot areas 20 as shown in FIG. 2. Sagging of the dry film photoimageable material used for forming the nozzle holes can result in non-functioning of the micro-fluid ejection head and/or severe performance defects in the operation of the micro-fluid ejection head.
Another problem associated with laminating materials to a semiconductor substrate for a micro-fluid ejection head is that such substrates are typically slightly bowed. During a lamination step wherein the substrates contain fluid supply slots therethrough, a vacuum chuck is unable to apply vacuum over the surface in order to effect substantial planarization of the substrate for lamination of materials thereto. Accordingly, there remains a need for improved methods of making micro-fluid ejection heads and for reducing the incidence of non-planarization of the components of the ejection heads so that operability and improved performance may be achieved.
Exemplary embodiments of the present application provide methods for making a micro-fluid ejection head structure and structures made by the methods. One such method includes planarizing a heated substrate component of a micro-fluid ejection head structure by applying a clamping voltage to an electrostatic chuck sufficient to hold the substrate component in a planarized orientation. A polymeric nozzle layer is laminated to the heated substrate component in a manner sufficient to provide a planarized nozzle layer on the substrate component.
In another embodiment, there is provided a micro-fluid ejection head structure having a substrate component. The substrate component includes a semiconductor substrate having a device side and one or more fluid feed slots therein. A flow feature layer is attached adjacent the device side of the semiconductor substrate. A nozzle film is laminated to the flow feature layer. During lamination of the nozzle film to the flow feature layer, the substrate component is electrostatically clamped to a chuck that is positioned over the nozzle film in a bonding orientation. In this orientation, the substrate component overlies the nozzle film and the device side of the semiconductor substrate is substantially downwardly facing such that gravitational forces inhibit deformation of portions of the nozzle film toward the device side of the semiconductor substrate.
Yet another exemplary embodiment provides a method of bonding a deformable film to a fluid flow structure in order to inhibit blocking of flow paths in the fluid flow structure. The method includes positioning a fluid flow structure on a first electrostatic chuck support surface. The deformable film is positioned on a second electrostatic chuck support surface. The first and second electrostatic chuck support surfaces are moved toward one another to thermally bond the fluid flow structure and deformable film to one another. During the bonding step, electrostatic forces inhibit deformation of portions of the film into the flow paths of the fluid flow structure.
An advantage of certain of the embodiments described herein can be that bowing of a semiconductor substrate may be substantially eliminated. Another advantage of the exemplary embodiments can be that sagging and other deformations of a film into the slots or flow feature areas of the semiconductor substrate structure, as occurs with conventional lamination techniques, may be substantially avoided.